Please explain 9mm grain weight differences

[spirit4earth]

I had assumed that 124 and 147 would be harder on a handgun than 115gr, but I was reading some stuff that implied that isn’t true. Is it harder on the gun to shoot 124 or 147 (fmj) regularly?
Thanks!

 

[Trooperdan]

Harder on the gun? Unlikely as I haven't seen any 147 gr designated as +P. In fact, I think the new Federal Fusion 150 gr 9 mm at about 850 FPS is gentler than 115.

 

[tjpopkin]

grain weight should not adversely affect the barrel...The 147gr bullets are usually subsonic and fairly easy to shoot, except your sights may vary with each load....usually vertical variation... heavier bullets tend to shoot higher.
In my experience, the S&W guns tend to be more accurate with 124gr.
My best (most accurate) load is 124gr Montana Gold Bullet over 5.0 gr. of VV-N330.

 

[Roller Delayed]

It really depends on the gun and the load. Delayed blowback guns can bet quite beat up by subsonic ammo because the chamber remains pressurized longer.

Recoil operated pistols aren't affected by that, but are affected by the actual recoil impulse - which can often be higher with subsonic. This is going to mean slide is going to impact at the rear harder.

Lightweight bullets like 115 get into the rifling sooner, so more of their powder is burned in the bore rather than in the casing like with 147. This is less of an issue with an auto, but of concern for revolvers due to flame cutting.


The most effective 115 loads are going to be +P and very fast. So that is more peak chamber pressure and more barrel friction wear than a subsonic load that isn't made in +P.


Some gun designs wear out due to recoil, others from bore erosion and others from pressure on locking surfaces. That's why it is going to depend.

 

[JohnHL]

If all bullets, regardless of weight, left a given pistol at the same speed (or velocity), the heavier the bullet, the heavier the recoil (and subsequently, harder on the gun).

But velocity DOES play a big part.

Randy Johnson, throwing a relatively light 5 oz. baseball at 100 mph, would produce considerably more force and damage than a six year old child rolling a 16 lb. bowling ball at 2 mph.

John

 

[Joed49]

I've found the 147 gr bullets to be more accurate out of any 9mm I own.

 

[spirit4earth]

So 115gr is not necessarily “easier” on a handgun like the 9c? If 124 is safe for the gun, I might try that since that’s what my SD ammo is.

 

[Roller Delayed]

So 115gr is not necessarily “easier” on a handgun like the 9c? If 124 is safe for the gun, I might try that since that’s what my SD ammo is.

115 practice ammo is likely easier on your gun - and cheaper.

 

[.38SuperMan]

I've found the 147 gr bullets to be more accurate out of any 9mm I own.

Something I’ve recently experienced in my 9mm Springfield is improved accuracy using hollow base plated round nose bullets vs non hollow base plated RN of the same manufacturer and weight. I’m using Berry’s plated bullets. Berry’s attributes the increase in accuracy to the increased surface contacting the rifling in the barrel. They claim mire surface contact yields better stability and accuracy.

A 147 should have greater surface and contact than a standard design RN 124 or 115. The hollow base bullets are longer giving a similar increase in contact surface.

 

[Roller Delayed]

Something I’ve recently experienced in my 9mm Springfield is improved accuracy using hollow base plated round nose bullets vs non hollow base plated RN of the same manufacturer and weight. I’m using Berry’s plated bullets. Berry’s attributes the increase in accuracy to the increased surface contacting the rifling in the barrel. They claim mire surface contact yields better stability and accuracy.

A 147 should have greater surface and contact than a standard design RN 124 or 115. The hollow base bullets are longer giving a similar increase in contact surface.

What kind of accuracy change are we talking about? A smooth bore 4" barrel fired from a test fixture will put all the round in an inch at 25 yards. Most of the accuracy changes in autos doesn't have anything to do with bullet stability at typical handgun distances but the way the slide and barrel behave under different kinds of recoil impulses.

Fixed barrel 9mms seem to produce 1" 25 yard groups with almost any ammo, in my experience.

 

[chief38]

In my Sig P365 the 115 grain bullets shoot 1.25" - 1.75" low (@15 - 30 ft) depending on brand. The 124 grain bullets shoot POA=POI no matter which brand I've tried. Haven't tried 147 grainers yet..... See what your guns like. For SD I prefer the 124's anyway.

 

[LoboGunLeather]

Does everyone understand that "grain" is a unit of weight measurement? 7000 grains to the pound, 437.5 grains to the ounce.

A 124-grain bullet is heavier than a 115-grain bullet, and a 147-grain bullet is heavier than either the 124 or the 115. Bullet weight (mass) combined with velocity equates to kinetic energy, displayed by both impact energy of the bullet and by recoil energy absorbed by (and used by the firearm in cycling).

Nothing magical about a particular bullet weight; just one of several factors affecting overall performance.

 

[Nevada Ed]

Things that are hard on weapons are...........

High chamber pressures.........

High temperatures of burning powder gases.......

Slides coming to the rear at high speeds.......

and copper bullets going down the barrel.

Pick your poison.